The present invention concerns a process for a radio communication system which is arranged for packet data transmission according to a message-synchronized ALOHA protocol with reservation. The invention concerns a process for requesting access in a momentarily overloaded mobile radio system wherein an access request received in a ase station from each station in a first group of mobile stations cannot be responded to by channel reservation for the first group of mobile stations.
The invention also concerns a base station and a mobile station in a radio communication system for packet data transmission.